Muhammad Fahad Ansari 12IEEM14

1. GLYCERINE
DISTILLATION
PLANT
Muhammad Fahad Ansari 12
IEEM 14

2. Method Of Production:
The Glycerol is derived from the direct
Saponification of Fats & Oils with Caustic Soda
and recovery as a By-product from the resulting
Soap.
During the Saponification Process,
glycerol is librated and then extracted by the
counter current washing of soap to obtain Spent
Lye which contains maximum concentration of
glycerol in water and impurities i.e. Soap, fatty
acids, color bodies, insoluble materials and
phosphorous and nitrogen compounds.

3. Saponification Reaction:
Triglyceride + Caustic Soda ----
Glycerol + Soap

4. Glycerine Manufacturing Process:
The Process Of Recovering glycerol
from soap lyes can be divided into the
following stages;
• Chemical Treatment (Purification Of Soap
Lye)
• Evaporation (Concentration Of Lye To Crude
Glycerine)
• Separation Of Salt And Preparation Of Brine
• Crude Glycerine To Produce marketable
Grades

5. 1. Purification Of Soap Lye:
The Chemical Treatment Of Soap Lye is designed to
maximize the removal of dissolved soap and other organic
impurities prior to evaporation and distillation. The most
common method for the purification of Soap Lyes consist of
two stages.
• The addition of Hcl (acid) and a Alum (coagulant) followed by
filtration
• The addition Alkali (Caustic Soda) to the filtrate to precipitate
the excess of Coagulant followed by filtration.
• Then the final filtrate is used as the feed to the evaporators.
Filtration:
Filtration is important in the Chemical treatment. When the
well agitated mixture is pass through the filter a clear filtrate is
produce. Plate & Frame type filter is commonly used.

6. 2. Concentration Of Glycerol
Liquors:
Purified soap lye are concentrated by evaporation
under reduced pressure (vacuum) to produce crude glycerine
containing 80-85% glycerol. Evaporation may be achieved by
two stages.i.e Single Effect Evaporator(40% half crude) and
then followed by finishing to 80-85% concentration at Double
Effect Evaporators.
Operation:
In the evaporation process, Concentration of glycerol is
accomplished by boiling out water. With soap lye liquors the
evaporation must be carried out in such a way that the salt, as
it Crystallizes from hot liquors,can be removed without
allowing it to be deposited on the heating surfaces of the
evaporator.

7. Single Effect Evaporation:
Steam is used as a heating medium in an Internal Shell
and tube heat exchanger.The liquor goes through the tubes by
natural circulation.Salt is removed from the system using a salt
box.
Double Effect Evaporation:
This type consists of two evaporators coupled in series.
Live steam is admitted to the first effect (evaporator). The
resultant vapour is used as a heating medium in the Second
effect. The transfer of process liquor between effects is
achieved by utilizing the difference in pressure in each effect.
Effective condensate removal is necessary between each
effect.The second effect usually operates at about 760 mm Hg
of vacuum,and the first effect about 300 mm Hg lower. Salt is
continuously removed from the system along with glycerol
liquors.

8. Salt Crystallization:
During the evaporation process,as water evaporates, salt
and glycerol concentration increases and solid salt starts
crystallizating.
The solubility of salt is seldom effected by temperatures,
and is principally controlled by the concentration of glycerol
present. Salt can be removed by using Salt Box.
Salt Box:
This is fitted to the bottom of the evaporator. It is
designed to steam the glycerol out of the salt, and return the
liquor to the evaporator.
Storage and Handling Of Crude:
After that, Crude glycerine is stored into large conical
tanks to allows a large amount of salt is settle down for at least
six hours is recommended that.

9. 3. Refining Of Glycerine:
Refining Of Glycerol is accomplished by Steam
distillation to separate high boiling, heat sensitive substances
like glycerol from water soluble and other impurites.The
distillation process utilizes two principles, Steam distillation
coupled with fractional condensation, followed by fractionation
to produce extra pure refined glycerine.
Distillation:
The concentration of glycerol in the crude feed to the
still is around 85-88%. To distill glycerol, it must be heated to a
temperature where its vapour pressure is greater than the
partial pressure of the glycerol vapours in the still. The vapour
pressure of pure glycerol is 760 mm (atmospheric) at 270
Centigrade. Since glycerol polymerizes at 160 Centigrade, the
partial pressure of glycerol is reduced by Vacuum System,
maintaing the same total pressure, and thereby allowing the
glycerol to vaporize at a lower temperature.
Chemical Reactions:
At the Still temperature, glycerol polymerizes in the
presence of caustic soda to form polyglycerols which
adversely effect the yield.

10. Condensation of Vapors:
After the vapors leave the still, they must be condensed.
Vapors contain water vapor and volatile impurites as well as the
glycerol. Success in producing good quality of refined glycerine lies in
the effectiveness of partial condensation. As the vapors pass through
these condensers, partial condensation takes place. Since the vapor
pressure of glycerol is much higher than that of water, relatively pure
glycerol is condensed at higher temperatures. Volatile substances
close to the boiling points of glycerol will condense along with pure
gkycerine, which acts as an impurity needing either redtisllation,
fractionation, bleaching deodorization.
Product removed from the condenser (99.5% wt. percent) are
subjected to a continuous Carbon Bleaching.
Deodorization:
Impurities found in crude Glycerine, especially MONG (Matter
Organic Non Glycerol), it can cause odor, taste, color problems in the
refined Product. Trimethylene glycol, a constituent of MONG, often
effects the color of the product.
In the Deodorizer (Carbon Bleaching System), 3-5% Charcol
(Activated Carbon) is introduced in the Bleacher to improve the color.
Such an effectiveness system to produces a product of 99.5%
high quality of CP (Chemically Pure) Grade Glycerine.